1. Field of the Invention
The present invention relates to a liquid crystal display device for forming images by applying a voltage to a liquid crystal material held between substrates, and to an electronic apparatus using the liquid crystal display device. More specifically, the present invention relates to an optical scattering layer of a liquid crystal display device.
2. Description of Related Art
Liquid crystal display devices produce displays by controlling the polarizing direction of incoming light. Such liquid crystal display devices can be broadly divided into three types including a reflective liquid crystal display device which utilizes light coming in from the front face of the device, a transmissive liquid crystal display device which utilizes light coming in from the back face or side face of the device, and a transflective liquid crystal display device which has both functions of a reflective liquid crystal display device and of a transmissive liquid crystal display device.
Generally, these liquid crystal display devices have a layer which scatters outgoing light, in order to widen a display-recognition angle, i.e., a viewing angle of a viewer.
As one process for forming such an optical scattering layer, there is provided a forming process in which fine particles, which have a refractive index different from that of the resin, are kneaded and dispersed in a resin. The resulting article is applied onto the overall surface of a substrate by, for example, a spin coater process or a roller coating process. The applied article is cured, and then necessary portions are patterned.
As the dispersion in radius of fine particles kneaded in the resin is inappropriate, a liquid crystal display device exhibits coloring which varies with angles at which the liquid crystal display device is viewed. Accordingly, there is a problem in that a display in color which a designer intends cannot be produced at some viewing angles, to thereby deteriorate display quality. Additionally, there is a drawback in that the display darkens when displayed in color.
The present invention has been accomplished at least in view of the aforementioned circumstances. One object of the present invention is to at least provide a liquid crystal display device and an electronic apparatus in which a hue does not change with viewing angles, and which are bright and are legible and are excellent in display quality, even when the scattering efficiency of an optical scattering layer is increased.
In a liquid crystal display device according to one exemplary embodiment of the present invention, the liquid crystal display device includes a pair of substrates, liquid crystal held between the substrates, an electrode formed on at least one of opposite faces of the individual substrates, and an optical scattering layer which is formed on at least one of the substrates. The optical scattering layer may include a resin and fine particles which are dispersed in the resin and have different refractive indexes from that of the resin. The fine particles having such a dispersion in radius may be contained in the resin of the optical scattering layer that light which has passed through the optical scattering layer and has been scattered has a dispersion in light tristimulus values, X value, Y value, and Z value falling within 10% at each angle in an angle range from 5xc2x0 to 20xc2x0 with respect to the traveling direction of incoming light.
In this exemplary embodiment of the present invention, a configuration in which the optical scattering layer constitutes a color filter is desirable. According to this configuration, a display screen which exhibits no coloring regardless of viewing angles, is bright, and is legible even when a color filter is provided can be obtained.
Additionally, it is preferable that a transparent resin film for flattening is formed on a surface of the optical scattering layer. According to this configuration, a color filter constituting a flat optical scattering layer can be manufactured, and a high display quality can be obtained.
Additionally, it is desirable that the optical scattering layer is formed on an opposite face of at least one substrate of the pair of opposing substrates. According to such a configuration, a clear display can be obtained without blurring the display.
Alternatively, it is preferable that the optical scattering layer is formed on an outside face of at least one substrate of the pair of opposing substrates. By configuring like this, a bright and legible liquid crystal display device can be stably supplied at low cost.
Furthermore, it is preferable that an optical reflecting layer is formed on either face of one substrate which becomes the underside of the pair of opposing substrates when viewed from a viewer side, and the optical scattering layer is formed between the optical reflecting layer and a liquid crystal layer. By configuring like this, a liquid crystal display device which effectively uses an extraneous light and is low in power consumption can be provided.
Additionally, it is preferable that the fine particles having such a dispersion in radius are contained in the optical scattering layer so that, with respect to light coming in from the direction at an angle of 25xc2x0 with respect to the direction of the normal line to the liquid crystal display device, light, which has passed through the optical scattering layer, has been reflected by the optical reflecting layer, has then passed through the optical scattering layer again, and has been scattered, has a dispersion in light tristimulus values, X value, Y value, and Z value falling within 10% at each angle in an angle range from 0xc2x0 to xe2x88x9225xc2x0 with respect to the direction of the normal line to the liquid crystal display device. By configuring like this, a liquid crystal display device in which a hue does not change with viewing angles, and which is legible and is excellent in display quality can be provided even when a display utilizing an extraneous light is produced.
Additionally, it is preferable that an optical reflecting layer is formed on either face of one substrate which becomes the underside of the pair of opposing substrates when viewed from a viewer side, and the optical scattering layer is formed on either face of one substrate which becomes the upper side when viewed from a viewer side. By configuring like this, a liquid crystal display device which effectively utilizes an extraneous light and is low in power consumption can be stably provided at low cost.
Additionally, it is preferable that the optical scattering layer is formed on the underside face of one substrate which becomes the underside of the pair of opposing substrates when viewed from a viewer side, and an optical reflective layer is formed on the surface of the optical scattering layer. By configuring like this, a liquid crystal display device which effectively utilizes an extraneous light and is low in power consumption can be stably supplied at low cost.
Furthermore, an electronic apparatus according to another exemplary embodiment the present invention includes the aforementioned liquid crystal display device. According to the exemplary embodiments of the present invention, a hue does not change with viewing angles, and a bright and high-contrast display screen can be obtained by optimizing the dispersion in radius of fine particles contained in a resin in the formation of an optical scattering layer.